\(\mathbf {h}_\mathrm {f}^{(l+1)} = \arg \min _{\mathbf {h}_\mathrm {f}} \frac{1}{2}\Vert (\mathbf {y} - \mathbf {F} \mathbf {h}^{(l+1)}) - \mathbf {F} \mathbf {h}_\mathrm {f} \Vert _2^2 + \lambda \Vert \mathbf {h}_\mathrm {f} \Vert _1\) , solved by the algorithm proposed in [1]};
